The most common and most likely answer to this crossword clue is the 10 letter word LUMBERJACK
I've seen this crossword clue in The Daily Telegraph
L
U
M
B
E
R
J
A
C
K
Buddy explains!
The straight part
We know that "Hazel’s possibly knocked down by him" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case hazel’s possibly knocked down by him = lumberjack.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does LUMBERJACK mean?
LUMBERJACK noun- A person whose work is to fell trees.
- A lumberjacket.
- To work as a lumberjack, cutting down trees.